Double-ended tube



Feb. 21, 1967 L. FElNsTs-:I ETAL 3,305,747

DOUBLE-ENDED TUBE Filed May l5, 1952 BY l Ml v AT ToRNE Y United States Patent Ofice 3,305,747 DOUBLE-ENDED TUBE Lester Feinstein, Bellerose, and Mortimer E. Weiss, Flushing, N.Y., assignors, by mesne assignments, to Sylvania Electric Products Inc., Wilmington, Del., a corporation of Delaware Filed May 15, 1952, Ser. No. 287,982 6 Claims. (Cl. 313-317) The present invention relates to electron discharge devices and particularly to a novel form of structural arrangement whereby the mount is supported within the envelope.

An object of the present invention is to improve the structure rigidity and ruggedness of thermionic discharge devices.

Another object of the present invention is the provision of a supporting structure for the mount of an electron discharge device of improved rigidity.

Another object of the present invention is the provision of an electron discharge device, as aforesaid, which may be fabricated on conventional electron discharge device manufacturing machinery.

Still another object of the present invention is the provision of an electron discharge device, as aforesaid, which does not require the use of a side exhaust tube or special positioning of the bulb in the exhaust machine used for manufacturing the tube.

Still a further o'bject of the present invention is the elimination of expansion relief structures within a tube as aforesaid.

The foregoing objects and others which may appear from the following detailed description are attained in accordance with the principles of the present invention by providing an electron tube mount structure having elongated connection leads extending oppositely beyond the mount, and first sealing leads in a header of the tube and then sealing leads into the glass envelope at the time the tube is tipped off. Preferably, the glass envelope is so shaped at the crown that an irregularly shaped aperture is provided for receiving support leads extending above the mount, the leads fitting into extreme portions of the irregularly shaped aperture. At the sealing operation the glass of the envelope is allowed to collapse in around the leads due to a pressure differential between the inside and outside of the tube, and to make a seal to the leads at the time the tube is tipped off.

The present invention will be more fully understood by reference to the following detailed description which is accompanied by a drawing in which:

FIG. 1 illustrates in elevation and partly in section, an embodiment of the present invention, while FIG. 2 is a fragmentary perspective view, partly in section, of a modification of the form of the invention shown in FIG. 1, while FIG. 3 illustrates the tube of FIG. 1 during the process of manufacture before the tube is sealed or tipped oii", While FIG. 4 is a transverse view, taken along line 4-4 of FIG. 3.

FIG. 5 is like FIG. 3, a longitudinal sectional view of a tube in the process of manufacture before being sealed off, but illustrating the modification of FIG. 2 rather than that of FIG. 1 as is the case with FIG. 3, and

FIG. 6 is a view taken along line 6 6 of FIG. 5.

Referring now to FIG. 1, there is shown an electron discharge device having an envelope 10 to which at one end is hermetically sealed a glass header 12 having a number of lead-in conductors 14 hennetically sealed through the header. Leads 14 extend above the header and through appropriately spaced apertures in spacer discs 16 and 18 which are usually punched out of thin 3,305,747 Patented Feb. 21, 1967 mica sheet and also serve as supporting members for the electrode structure. The discs are of such diameter as to fit closely within the tubular wall of envelope 10 and aid in supporting the mount structure of the tube within the envelope. The mount structure, as illustrated in FIG. 1, includes a filamentary cathode 20 passing through triangular holes such as that shown at 21 in FIG. 1, in micas 16 and 18, a corner of the triangle being at the center of discs 16 and 18 so as to centrally locate the lilamentary cathode 20 within the tube. Surrounding the filamentary cathode 20 are a number of control grids, one of which is shown at 22, and an anode 24 maintained in proper spacial relationship with regard to cathode 20 and grids 22 by being secured to certain of the extended lead-'in conductors 14. Where a filamentary cathode such as 20 is employed we prefer to suitably tension the cathode by a tension spring arrangement 26 having a V- shaped portion, the apex of which is secured to the filamentary cathode and the ends of which are formed into helical springs on the extending arms of spring support structure 28. Spring support structure 28 is welded or otherwise secured to one of the lead-in conductors 14 whereby it is secured in position and, due to tension on the spring, maintains a predetermined tension on the filamentary cathode 20. The lower end of iilamentary cathode 20 is secured to a fixed support which may be carried by another one of the vlead-in conductors 14 in a conventional manner not shown in this drawing, since it constitutes no part of the present invention.

As shown in FIG. 3, the envelope 10 is adapted for exhaust and sealing by an upwardly extending tubular portion 11 which is necked down at 30 to facilitate sealing off` and in the same region is also flattened into an oval configuration, as shown in the cross-sectional View of FIG. 4, to provide a slot into which three of the lead-in conductors identified in the figures by reference characters 14a, 14h, and 14e extend and by which they are positioned relative to one another before sealing. The modification shown in FIGS. 1, 3 and 4, has conductor 14b cranked so that its upper end lies in the same plane as conductors 14a and 14C.

In the manufacture of the tube, after the envelope is exhausted and the elements bombarded, region 30 of the envelope is heated and allowed to collapse about the ends of leads 14a, 14b and 14c thus rigidly securing them in position sealing off exhaust aperture 11 to maintain the vacuum within the tube as shown in FIG. l.

It will be noted that during the preliminary stages of evacuation of the tube when it is required that the elements be heated to remove occluded gases therein, the leads may expand freely since they are at that time unsupported at the top end of the tube. Thus there is no necessity for the provision of expansion reliefs in these conductors. However, at the time the tube is tipped off the lead-in conductors and the tube mount itself have attained temperatures which do not differ substantially from those attained during normal operation and the collapse of the glass about the upper ends of the leads to form the seal-off rigidly secures them in position.

The modification of the invention shown in FIGS. 2, 5 and 6 differs from that shown in FIGS. l, 3 and 4 essentially in that four lead-in conductors 14 extend through the mount and are received in the corners of a generally rectangular formation of the glass at the sealing off point. Where the same elements appear in these figures as appeared in FIGS. 1, 3 and 4 the same reference characters are employed. Conductors 14a and 14e are disposed exactly as they are in the previously described figures, and in this modification, the conductors identified by reference characters 14d and 14e likewise extend in substantially straight lines parallel to the axis of the tube, forming a rectangular configuration as shown in FIG. 6. The portion of envelope 10 where the seal off is to take place is, in this modification, provided with four longitudinally extending depressions 31 along the length of the necked portion 30 thus forming an approximately star shaped figure having four points into the corners of which each of the extended conductors 14 extend.

FIG. 2 shows how the glass in the sealing olf operation collapses about the conductors 14a, 14e, 14a', and 14e to form a solid seal-off tip having a slightly fluted exterior surface.

It will be noted that our present invention provides a more rigid type of mount structure in that the leads extend in substantially straight lines through the tube and are rigidly secured in position at each end, while at the same time the expansion reliefs which have heretofore been considered necessary in prior types of double ended tubes are avoided, as is the necessity for the use of a side exhaust tubulation. Also the tube of the present invention may easily be fabricated, tipped off and sealed in manufacturing machinery of the type which is designed for use with more conventional tube constructions. In some instances, it 4may be found desirable to extend conductors 14 through the glass tip-olf to serve as additional connections to the tube. Techniques for protecting the extended leads from coating with glass over the exposed portions are known in the art.

While we have particularly shown and described a number of embodiments of the present invention, it should be clearly understood that our invention is not limited thereto but that modifications within the scope of the claims may be made.

What we claim is:

1. A double ended electron discharge device having an electrode structure, a rst group of supporting members extending away from said structure and sealed in a header, an envelope surrounding said structure and sealed to said header, a second group of supporting members extending from said electrode structure oppositely of said first group, an exhaust aperture in the envelope having peripheral recesses adapted to position said second group of supporting members with respect to said envelope, whereby said envelope may be exhausted through said aperture and then hermetically sealed by closing said aperture around said second group of positioned supporting members.

2. An electron discharge device having an electrode structure, a first group of supporting members extending away from said electrode structure and hermetically sealed in a header, an envelope surrounding said electrode structure and hermetically sealed to Said header, anv aperture in said envelope having a number of recesses around the inner periphery thereof, a second group of supporting members extending away from said electrode structure oppositely of said first group extending into said aperture and maintained in position relative to said envelope by said recesses, whereby said envelope may be exhausted and sealed at said aperture while maintaining said second group of supporting members in said position.

3. In a method of assembling electron discharge device electrode structure having supporting members with a supporting envelope, the steps which include forming said envelope with an exhaust tubulation having interior peripheral recesses, inserting said electrode structure within said envelope with its supporting members positioned within said recesses, exhausting said envelope through said tubulation, and heating said tubulation to cause it to ow about said supporting members and to form a hermetic seal therewith.

References Cited by the Examiner UNITED STATES PATENTS 1,624,451 4/1927 Weinhart 313-285 1,859,677 5/1932 Nachumsohn 313--284 2,129,849 9/1938 Laico 313-285 2,343,457 3/1944 Herzog 313-290 2,380,757 7/ 1945 Herne 313-285 2,478,969 8/ 1949 Ishler 313-286 JOHN W. HUCKERT, Primary Examiner.

JAMES L. BREWRINK, WILLIAM G. WILES,

A. M. LESNIAK, I. H. LINSCOTT,

Assistant Examiners. 

1. A DOUBLE ENDED ELECTRON DISCHARGE DEVICE HAVING AN ELECTRODE STRUCTURE, A FIRST GROUP OF SUPPORTING MEMBERS EXTENDING AWAY FROM SAID STRUCTURE AND SEALED IN A HEADER, AN ENVELOPE SURROUNDING SAID STRUCTURE AND SEALED TO SAID HEADER, A SECOND GROUP OF SUPPORTING MEMBERS EXTENDING FROM SAID ELECTRODE STRUCTURE OPPOSITELY OF SAID FIRST GROUP, AN EXHAUST APERTURE IN THE ENVELOPE HAVING PERIPHERAL RECESSES ADAPTED TO POSITION SAID SEC- 